The present invention relates to a method of treating a high-level radioactive waste liquid produced in a reprocessing plant. More specifically, the present invention concerns a method of treating a high-level radioactive waste liquid wherein the high-level radioactive waste liquid is largely classified into (1) condensate, (2) bulk wastes mainly containing sodium nitrate, sodium hydroxide, etc., and (3) a residue comprising fission products, actinoids, and corrosion products (iron, chromium, nickel, etc.) occurring in a reprocessing process, including nitrate, oxides, etc., and wherein (1) the condensate and (2) sodium nitrate, sodium hydroxide, etc., are converted into a low-level radioactive waste, and the amount of the residue including fission products, actinoids, and corrosion products is reduced substantially by removing (3) sodium nitrate, sodium hydroxide, etc. In this method, as the residue is stored in the form of nitrate, oxides, and the like, storage is facilitated, and recovery of useful elements in the future is made possible as the residue containing useful elements is separated.
Hitherto, as a method of permanently separating radioactive wastes from an environment without requiring artificial operations, a glassification treatment process is adopted in which waste is provisionally stored as a liquid for a certain period and is then glassified to ensure that the radioactive substances contained in the waste will not move for a long period of time. The radioactive waste liquid produced in a reprocessing plant is mainly constituted by a large amount of sodium nitrate and sodium hydroxide, and disposal of this waste liquid is effected by dissolving the waste together with a large amount of a glass-forming agent, thereby effecting the aforementioned glassification treatment.
However, when glass having good qualities (properties) is formed in this glassification treatment, the amount of sodium that can be contained in the glass is limited. Consequently, there is a drawback in that it is difficult to convert a large amount of high-level waste liquid into a small amount of a glassified body, with the result that the amount of glassified body produced becomes disadvantageously large.
In addition, since the high-level radioactive liquid is heated and dissolved at a high temperature, there is the problem of the component materials of equipment from becoming corroded. Hence, when a need arises in the future to recover useful elements, the separation and recovery of useful elements are estimated to be difficult.